In large bowl combine flour, salt and cream of tartar.
In separate bowl combine water and oil together.
While constantly stirring add water/oil to the flour mix. When dough becomes too stiff to blend with a spoon its time to start using your hands.
Transfer dough to floured work surface and knead dough until all the flour is incorporated.
Add more flour if necessary, until dough is no longer sticky.
Separate dough into pieces. (how ever many different colours you want)
Add about 1/8 teaspoon of food colouring and knead into playdough. (Be sure to wear disposable gloves until food colouring is worked into the playdough).
Store playdough by wrapping tightly with plastic wrap and ziploc bags.